Please only answer this question if you fully understand the rules of transfiguration in HPMOR.
At the end of HPMOR, why didn't Harry transfigure multiple Sorcerer's Stones and use the original Stone to keep the transfigurations in place? The book states that only one stone was ever made due to the diffuculty of the process. And although unstated, although the rules of transfiguration in HPMOR state that merely envisioning the result is enough for transformation to take effect (no matter how complicated it is to make the object normally), it is understandable why no one else tried to transfigure an object into a Sorcerers Stone - because the transfiguration could not maintained forever and the elixir of life would be unsafe to consume.
But once Harry has the original stone, which can render transfigurations permanent, he should be able to transfigure multiple stones. So why doesn't he?